Answer:
The correct answer is: β1 adrenergic receptor activation. Increased in cAMP lead to increased amounts of Na influx (though if channels) and calcium influx of pacemaker cells. This increases the frequency of APs of the pacemaker and increases the rate of contraction.
Explanation:
cAMP generated in response to β1 adrenergic receptors,results in excitation contraction coupling by initiating PKA and causing phosphorylation of L type Ca2+ channels and ryanodine receptors. This increases the concentration of intracellular Ca2+ ions in atrial cells, ventricular cells and AV pacemaker cells. This increase in firing rate. As a result rate of contraction increases.
During meiosis, two successive nuclear divisions happens namely Meiosis I or reduction and Meiosis II or division. In meiosis I, it separate chromosomes after allowing crossing over. In meiosis II, it the then separates each chromosomes by splitting them. This division produces 4 haploid cells.
Answer:
We may consider bees good because they pollinate the plants that give us food crops. We may consider mosquitos bad because they can transmit malaria.
1) Enzyme activity
2) Cell to cell recognition
3) Cell signalling
4) Transport Materials.
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